1. Field of the Invention
The invention relates to light emitting diodes, more particularly to a method of manufacturing a string of electrically connected light emitting diodes.
2. Description of the Related Art
Referring to FIG. 1, a conventional method of manufacturing a string of electrically connected light emitting diodes is shown to comprise the following steps:
providing a work table 1 having a working surface formed with a number of spaced recesses 1a (only one is shown); PA1 providing a number of light emitting diodes 2 (only one is shown), each of which has a light emitting portion 2a that is inserted into a corresponding one of the recesses 1a and a pair of terminals 2b that extend from the light emitting portion 2a (only one terminal 2b is shown); PA1 providing a pair of electrical conductors 3 (only one is shown), each of which has a conductive core 3a and an insulating sheath 3b around the conductive core 3a, the insulating sheath 3b being stripped at locations corresponding to the recesses 1a to form a number of exposed core portions; PA1 welding each of the terminals 2b of the light emitting diodes 2 to one of the exposed core portions of an adjacent one of the electrical conductors 3; and PA1 cutting excess portions of the terminals 2b, providing a number of inverted U-shaped base members 4 (only one is shown), each of which covers the weld between the electrical conductors 3 and the terminals 2b of one of the light emitting diodes 2, and filling each of the base members 4 with glue 5 to secure the base members 4 onto the electrical conductors 3. PA1 providing a number of base members, each of which is made of an insulator material and includes a base plate that is formed with a pair of first terminal holes, and a spaced pair of side walls that extend upwardly from the base plate and that confine a space therebetween; PA1 providing a work table having a working surface formed with a number of spaced recesses, each of the base members being received in a respective one of the recesses, each of the recesses having a bottom formed with a pair of second terminal holes that are aligned with the first terminal holes in the respective one of the base members; PA1 providing a number of light emitting diodes, each of which has a light emitting portion and a pair of terminals that extend from the light emitting portion and that are partially extended into the aligned first and second terminal holes in the respective one of the base members and the respective one of the recesses such that the light emitting portion is initially spaced apart from the respective one of the base members; PA1 providing a pair of electrical conductors, each of which has a conductive core and an insulating sheath around the conductive core, each of the electrical conductors extending through the spaces in the base members and being disposed between a corresponding one of the terminals of the light emitting diodes and a corresponding one of the side walls of the base members; PA1 pushing each of the light emitting diodes toward the respective one of the base members such that movement of the terminals further into the second terminal holes results in a cutting action of the terminals into the insulating sheaths to establish electrical contact between the terminals and the conductive cores of the electrical conductors while holding tightly the electrical conductors between the terminals of the light emitting diodes and the side walls of the base members; and PA1 removing the light emitting diodes, along with the base members and the electrical conductors, from the work table, cutting off excess portions of the terminals, and applying a layer of glue on a bottom side of the base plates of the base members.
Some of the drawbacks of the aforementioned conventional method of manufacturing a string of electrically connected light emitting diodes are as follows:
1. Once assembled, the distance between the terminals 2b of a light emitting diode 2 in the base member 4 is relatively small. Accidental movement of one of the terminals 2b during assembly can lead to undesired contact between the terminals 2b, thereby resulting in a short-circuit condition. In addition, the presence of weld beads between the electrical conductors 3 and the terminals 2b of the light emitting diode 2 increases the risk of a short-circuit condition.
2. Since there are many light emitting diodes 2 on the electrical conductors 3, detection of a short-circuited one of the light emitting diodes 2 is a time-consuming process that is made possible only after cutting the electrical conductors 3 into several segments.
3. The insulating sheath 3b is manually stripped at locations corresponding to the recesses 1a to form the exposed core portions. Aside from using up a lot of time and manpower, the stripping operation may result in accidental damage to the conductive core 3a.
4. Manual welding of the terminals 2b of the light emitting diodes 2 onto the electrical conductors 3 is a slow and laborious process.